Western Electric D-98548 Early Handset Telephone

[Payphone installer]

Little is known about this telephone. I think it was probably the first W/E handset model.

[Payphone installer]

Only one known to exist.

[Payphone installer]

Cast backboard

[Payphone installer]

Terminal strip is like no other. Rivets used instead of screws like in 160 series. Pile ups unique to this phone.

[Payphone installer]

Guts to upper housing also unique.

[Payphone installer]

BSP of telephone

[Payphone installer]

More BSP

[Payphone installer]

I do not believe my telephone has the proper hook. I am looking for the hook in the picture and will pay well of trade to get it. I think it probably looks like the hook on a early space saver except for a pin type shaft. 

[tallguy58]

Nice phone from 1938.

What type of dial is in there? Do all the dates match?

Also, in the 4th photo there's a metal horizontal bar marked "21". What is the purpose of that thing? I have a payphone and for the life of me can't figure out what it does.

[Stan S]

Hello
The part marked '21' is an equalizing spring.  When the top is on the payphone that spring applies forward pressure on the left side of the top equal to the forward pressure applied by the transfer contacts on the right side.
I believe that is the only complete example of that model payphone known to exist.

[Ktownphoneco]

That's a grounding spring, to ground the upper housing to the back plate.      There should be a bare anodized "U" shaped clip with a couple of notched teeth, placed over the edge of the upper housing, that rests against that spring loaded bar your referring to.      Once the upper housing is installed, the 2 devices should touch each other firmly, electrically connecting the two components.
There are significant voltages applied to the coin relay during the normal operation of a payphone, so proper grounding is an important issue.

Jeff Lamb

[Stan S]

Jeff
That part existed in every Western Electric 3-slot ever made from the model 50A designed in 1912 to the very last model 3-slot. The 'Tinnerman' clip you are referring to was first used on some (not all) newly manufactured 200 series 3-slots in the early 1960s.

The particular payphone pictured did not have the U shaped Tinnerman clip just like all the following 'new' manufactured models didn't: the 160s, the 180s and the 190s.

Was the clip eventually added to aid in grounding the top to the back of the payphone later on -probably.  However, in 1938 that was not its original purpose.  If you look at all the older Gray and Automatic Electric parts lists, that part is called out as 'EQUALIZING SPRING' Automatic Electric part number #P10296.

As far as grounding the top to the back of the phone having anything to do with the high voltage that is used to trigger the coin relay, I don't see that voltage having anything to do with the top being grounded or not. That voltage never leaves the bottom or reaches the top of the payphone.

The only safety concern I can see is if the payphone line took a lightning hit and a VERY unlucky person was using the phone at the same time.  U clip or no U clip, I wouldn't want to be him!

[Phonesrfun]

Jeff
That part existed in every Western Electric 3-slot ever made from the model 50A designed in 1912 to the very last model 3-slot. The 'Tinnerman' clip you are referring to was first used on some (not all) newly manufactured 200 series 3-slots in the early 1960s.

The particular payphone pictured did not have the U shaped Tinnerman clip just like all the following 'new' manufactured models didn't: the 160s, the 180s and the 190s.

Was the clip eventually added to aid in grounding the top to the back of the payphone later on -probably.  However, in 1938 that was not its original purpose.  If you look at all the older Gray and Automatic Electric parts lists, that part is called out as 'EQUALIZING SPRING' Automatic Electric part number #P10296.

As far as grounding the top to the back of the phone having anything to do with the high voltage that is used to trigger the coin relay, I don't see that voltage having anything to do with the top being grounded or not. That voltage never leaves the bottom or reaches the top of the payphone.

The only safety concern I can see is if the payphone line took a lightning hit and a VERY unlucky person was using the phone at the same time.  U clip or no U clip, I wouldn't want to be him!

As far as the voltages for the coin relay, or any other voltages for that matter not leaving their intended place, what if they did leave?  If an installer had inadvertantly smashed the upper housing against a wire and cut into it with the edge of the upper housing, then the upper housing could have an unwanted voltage on it. (Remote, I know).  Whether that be talking, ringing, or coin relay,  I would vote for the spring being dual purpose, if not that its primary purpose would be the grounding or equalization of the potential.

Early phones had their metallic bases and other metallic parts common to one side of the line.  I.E early transmitters with one wire and the metal case serving as the other side.  Didn't they isolate the metal base of the phone on purpose in later models?

[Ktownphoneco]

Stan & Bill   ....     Ok, that makes sense.       I haven't any experience on coin collectors prior to the 233's.    I was going solely on the information contained in BSP 506-110-200.       Section 2.07 on page 3, and Figure 5 on page 4.       I took a quick look through both my AT&T and Bell Canada Coin Collector service manuals, and didn't notice anything other than the reference to properly grounding the back plate and upper housing.    But as I mentioned, it was only a "quick look", so I may have missed some other important information regarding the issue.
Your joint explanations does make perfect sense, and if the Tinnerman clips didn't show up until the 200 series sets went into production, then obviously grounding the upper housing wasn't a priority issue, since the thickness of the paint applied to most coin collectors, would probably prevent the upper housing from actually having metal to metal contact with the spring mounted on the back plate, thereby not grounding the upper housing at all.

Thanks for that information.   Another lesson learned.    The attached BSP, was provided by, and downloaded from, the documents library of Telephone Collectors International with thanks.

Jeff Lamb

[Stan S]

Hey Bill and Jeff

Like the TV show said 'Return with us now to those thrilling days of yesteryear!' It's all a matter of the time in history when you grew up.

Remember, we are talking about a payphone dated 1938. In those days 2 prong AC plugs and outlets (no ground pin) with zip cord wire on AC- DC 5 tube radios with no transformer were 'state of the art'.  One side of the AC line was connected to the chassis screws that held it in the plastic case. God forbid if you plugged the NON POLARIZED PLUG in the wrong way, the hot side of the AC line appeared on the screw heads!!! 

It was a different world back in the 1930s before the liars (sorry) lawyers got involved with engineering.
Have you looked at a simple step ladder these day?  I can remember when the only sticker on a step ladder was the logo of the company that manufactured it.  Today every inch of the ladder is covered with warning stickers to limit the manufacturer's liability.

I'm absolutely sure the thought of that spring being used as ground never crossed the mind of the engineer who designed that part originally.  In a 233G-236G a small jumper was added to the design that connects the #3 (GND) screw terminal of the coin relay to the small screw on the rear right hand side of the top of the tray. The #3 screw on the coin relay is where the payphones' YELLOW external ground is connected to the outside world. That small jumper was added to ground the payphone case.  Originally the ENTIRE case was isolated. That jumper was never part of the original design.

I have to tell the folks that buy my controllers to take out that jumper.  If they have carpeting that produces static electricity every time they touch the case of the payphone the answer circuit of the phone takes it off hook because of the static electric spark.

Can the unexpected happen-sure. Can folks get hurt, unfortunately- yes.  Was it a good idea to use the clip to ground the top to the rest of the payphone- probably.  Was it originally used for that purpose-nope.
Stan